^Mann, George (1999). The Mammoth Encyclopedia of Science Fiction. Robinson. pp. 219–221. ISBN1-84119-177-9. "Some of Moorcock's genre fiction is borderline SF, though most of it is better described as fantasy. One of the most impressive aspects of this achievement is the way in which he has linked much of his fiction together into one monumental sequence, The Tale of The Eternal Champion. Central to this ongoing series is Moorcock's concept of the Multiverse. The Multiverse was introduced in Moorcock's early novel The Sundered Worlds and is an imaginative construct of transitorally intersecting parallel and alternate worlds, an infinite series of concurrent, sometimes intertwined universes between which the Eternal Champion moves."
^Heaphy, Maura (2008). Science Fiction Authors: A Research Guide. Author Research Series. Libraries Unlimited. p. 162. ISBN1-59158-515-5. "Much of Moorcock's sf is played out in the "Multiverse", a kaleidoscope of alternate realities that interconnect and shift in time. The Multiverse has subsequently been used, with Moorcock's permission and encouragement, by numerous other writers in their own stories."
^John Clute, John Grant (1999). The encyclopedia of fantasy. Macmillan. p. 668. ISBN0-312-19869-8. "A term coined by Michael Moorcok (also, earlier and independently by John Cowper Powys) to describe a universe consisting of innumerable alternate worlds, all intersecting, laterally and (palimpsest-fashion) vertically. Some of these parallel worlds operate according to SF premises, some - like the worlds in which various avatars of Moorcock's Eternal Champion series play out their linked destinies - operate in fantasy terms. Worlds governed by incompatible premises are not, however, barred from each other and in this sense the overall concept belongs more properly to fantasy than to Sf. Moorcock himself treats his extremely large and varied oeuvre as though all its venues occupy niches in the one multiverse."
^"Oxford English Dictionary". Retrieved 28 February 2010. "b. orig. Science Fiction. A hypothetical space or realm of being consisting of a number of universes, of which our own universe is only one; (Physics) the large collection of universes in the many-worlds interpretation of quantum mechanics, according to which every event at the quantum level gives rise to a number of parallel universes in which each in turn of the different possible outcomes occurs. 1963 M. MOORCOCK in Sci. Fiction Adventures 6 No. 32. 54 Jewelled, the multiverse spread around him, awash with life, rich with pulsating energy."